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Have the distributor electronics checked. I had an 84 Chevy 454 motorhome that hesitated like it was out of gas and then started up again before starting to run rough. The diagnosis resulted in the coil needing to be replaced. The problem that I am having with the timing diagnosis is that I would assume that if the timing was bad, it will continuously backfire. Marie22 states that it would backfire and then run fine for about 5 miles before backfiring again.

Have the distributor electronics checked. I had an 84 Chevy 454 motorhome that hesitated like it was out of gas and then started up again before starting to run rough. The diagnosis resulted in the coil needing to be replaced. The problem that I am having with the timing diagnosis is that I would assume that if the timing was bad, it will continuously backfire. Marie22 states that it would backfire and then run fine for about 5 miles before backfiring again.

If the coil is going bad it will back fire under load and usually idle and cruise with no issues. When a motor is back firing through the intake its because a cylinder is firing before the intake valve is fully closed which lights the fuel in the intake as well as the cylinder

I have been racing GM products for well over 25yrs and I have never ever heard of setting your timing on a GM vehicle using cylinder 5..... I mean EVER so who or where have you heard that from?

I have probably done 50 of these in 15 years. All on # 5 cylinder. Reference Chevrolet Motor Home Chassis service guide. The publication guide number is ST-95-MH . Page 7-69 (this is just one of many.) note view with timing light from underside of vehicle use # 5 cyl.

I have probably done 50 of these in 15 years. All on # 5 cylinder. Reference Chevrolet Motor Home Chassis service guide. The publication guide number is ST-95-MH . Page 7-69 (this is just one of many.) note view with timing light from underside of vehicle use # 5 cyl.

correct...also what usally happens here is lean pop..
if its a throttle body.....the injector pulses off the distributor

you can see it skip when it's shoot'n ducks...(pop'n up through the carb)

you can start throw'n parts at it or have some one that knows fix it...

I have probably done 50 of these in 15 years. All on # 5 cylinder. Reference Chevrolet Motor Home Chassis service guide. The publication guide number is ST-95-MH . Page 7-69 (this is just one of many.) note view with timing light from underside of vehicle use # 5 cyl.

So its motor home specific i never knew that thanks for setting me straight on it....